import turtle
colors = ['red', 'orange', 'yellow', 'green', 'cyan',
          'blue', 'purple']

colors = colors[4:]+colors[:4]
turtle.left(90)
turtle.pensize(21)
turtle.up()
turtle.goto(160, 0)
turtle.down()
for i in range(7):
    turtle.pencolor(colors[i])
    turtle.circle(160-i*20, 180)
    turtle.up()
    turtle.goto(160-(i+1)*20,0)
    turtle.down()
    turtle.left(180)

turtle.done()
